Tractor hydraulic fluid compositions are formulated to exacting and often stringent specifications set by equipment manufacturers or governmental regulations. Depending on the application, the compositions may contain dispersants, detergents, anti-oxidants, wear inhibitors, rust inhibitors, corrosion inhibitors, foam inhibitors, friction modifiers, and/or other additives, together with base oils of lubricating viscosity.
Tractor hydraulic fluids are all-purpose products used for lubricant applications in a tractor, including but not limited to lubrication of gearboxes, power take-off and clutches, rear axles, reduction gears, wet brakes, and hydraulic accessories. The components included within a tractor fluid must be carefully chosen so that the final resulting fluid composition provides all the necessary characteristics required for the particular application. Such characteristics may include the ability to provide proper frictional properties that prevent wet brake chatter of oil immersed brakes while simultaneously providing the ability to actuate wet brakes and provide power take-off (PTO) clutch performance. Tractor hydraulic fluids are used, e.g., in agricultural machines, e.g., for lubricating hydraulic pumps, transmissions, clutches, gears, and wet brakes. Agricultural machines are frequently operated in settings where water is present, e.g., rice paddies and humid climates. As such, lubricating oil compositions for agricultural machines must be formulated to provide the desirable lubricating properties while at the same time minimizing the impact of water contamination, e.g., brake chattering and brake noise.
Thus, there is a need for tractor hydraulic fluid compositions that provide desirable friction properties while preventing or minimizing the negative impacts of water contamination, e.g., brake noise.